90 MICROSCOPIC EXAMINATION OF BACTERIA. 



alcohol until the glass is clean. Dry and stain with anilin- 

 water fuchsin having a neutral reaction. Wash in water, 

 dry, and mount in Canada balsam. The stain is neutralized 

 with solution No. 2. If the organism produces alkalies, 

 solution No. 3 is added in the proportion of 1 drop to 1 c.c. 

 in 16 c.c. of the mordant. If the organism, on the other 

 hand, produces acids, solution No. 2 is added in the same 

 way. 



Loeffler has determined the exact quantity to be added to 

 each 16 c.c. of mordant solution for staining the flagella of 

 the following : 



Cholera spirillum, J-l drop of solution No. 3. 



Bacillus typhosus, 1 c.c. of solution No. 2. 



Bacillus subtilis, 20-30 drops of solution No. 2. 



Bacillus of malignant oedema, 36-37 drops of solution 

 No. 2. 



Van Ermengen's method, though complicated, yields very 

 satisfactory results. The film is placed in a fixing solution 

 consisting of 1 part of a 2 per cent, solution of osmic acid 

 and 2 parts of a 10 to 25 per cent, solution of tannin, for one 

 hour at the room temperature. It is then thoroughly washed 

 in distilled water, and the film transferred for a few seconds 

 to a 5 per cent, solution of nitrate of silver ; then into the 

 following for a few seconds : 



Gallic acid, 5 grams ; 



Tannin, 3 " 



Fused potassium acetate, 10 " 



Distilled water, 350 c.c. 



Return the film to the silver solution, allowing it to remain 

 there until it has turned black ; wash well in water, dry, and 

 mount. 



Pittfield uses a method which is both a mordant and a stain. 

 The solution is prepared as follows : 



Saturated aqueous solution of alum, 10 c.c. ; 

 Saturated alcoholic solution of gen- 

 tian-violet, 1 " 

 Mix well and filter. Add : 



